| 摘要 |
<p>PURPOSE: To obtain the oscillating circuit not affected by a transistor(TR) characteristic and a power supply fluctuation by comparing a voltage generated from a voltage generating circuit with a charging voltage of 1st and 2nd capacitors for charging/discharging respectively so as to control the oscillation. CONSTITUTION: A constant voltage constant current generating circuit 11 outputs two different constant voltages VrefH, VrefL and two constant currents IrefH, IrefL proportional to the difference of them. An amplifier circuit 12 compares a voltage Vcap with the constant voltage VrefH, VrefL respectively. A selection circuit 13 opens a switch S1 and closes a switch S2 till the voltage Vcap is equal to the constant voltage VrefH and then equals to the constant voltage VrefL. Thus, the capacitors C1, C2 are discharged by the constant current IrefL and the switches are operated reversely to above till the voltage Vcap is equal to the constant voltage VrefL and then equals to the constant voltage VrefH, and the capacitor is charged by the current IrefH. A prescribed period T1 of the oscillation circuit depends only on charging/discharging times TR, TF of the capacitors C1, C2.</p> |
